Vascular grafts are prosthetic medical devices used in a variety of medical procedures, including for forming an anastomosis in the course of repairing or replacing diseased vessels, or for purposes of hemodialysis (which may involve forming an arteriovenous fistula, in which a vascular surgeon joins an artery and a vein together using such a graft). A typical graft is a flexible, elongated, tubular structure made of a biocompatible material, and thus designed to mimic the vessel(s) being repaired or connected. An example of a typical graft G is illustrated in FIG. 1, which is quite simply an elongated tubular or pipe-like structure that may have a variety of diameters and lengths depending on the intended use.
In the course of forming the anastomosis, it is sometimes desirable to create a reduced diameter section for regulating fluid flow through the graft, which may avoid creating circulatory problems in other parts of the vasculature. One past manner of achieving this reduction is for the vascular surgeon to cut the graft longitudinally along an intermediate portion, overlap the portions created by the cut, and stitch them back together to provide the entire graft with a desired reduction in diameter. Obviously, this is a laborious and time-consuming step in an otherwise medically complex procedure, potentially taking hours to complete, and is highly dependent on the skill of the vascular surgeon. Moreover, the resulting graft may produce sub-optimal results if the stitching becomes undone over time, or perhaps even if a tear results as a result of the weakening of the graft material resulting from the cutting required.
To avoid these limitations, a past proposal has been made for a so-called “flow restriction graft” F, an example of which is shown in FIG. 2. This graft is of the same tubular, flexible structure as illustrated in FIG. 1, but includes a necked portion N that provides the desired decrease in inner diameter (e.g., from 7 millimeters to 3 or 4 millimeters). While this device solves the above problems with manual reductions achieved by cutting the graft, it does not account for the possibility that a variety of reductions in diameter may be required, depending on the needs of a particular patient or use to which the graft is put. Obviously, if a different reduced diameter is desired than would be provided by a flow restriction graft on hand, then the manual reconstruction may be necessitated, which potentially leads to the aforementioned problems.
Accordingly, it would be desirable to provide an adjustable vascular graft that allows for a custom inner diameter reduction to be achieved by the end user in an easy and highly repeatable manner. The graft would thus be useful in a variety of applications, and avoid the past need for having different graft sizes on hand. It would also allow for the reduction in diameter to be achieved quickly, without the need for extensive reconstruction of the graft and the concomitant issues that may result.